Alright, well I've discovered some rather bad rust on my 72, but it hasn't spread much and I'm worrying just how big a deal it is...

Basically, for a few inches of the frame in front of the rear tires...well, it's in baaad shape. It doesn't extend to the crossbrace that goes from the side rails (i.e. along the doors) to the rear crossmember. But for those few inches...it's bad. There are a bunch of large chunks/plates of rust sitting inside the rail, presumably from the inside, both top and bottom. On the right side it's especially bad, as there's a split through it...when I used my scissor jack on this area to change my spare tire, a decently large section of it kinda bent up. I've been hoping that because of the crossbrace that is perfectly intact, I don't have to put my car away for 15 years until I can do a frame-off I'll take some pics and post them up when I can...but I need to know how bad it is.

The rest of the frame is fine, no other rust problems whatsoever, really quite solid all around.

*EDIT* After looking at some pics...it seems like the crossbrace I'm talking about isn't supposed to be there? Perhaps the previous owner had this brace welded in so that the rust in this area wouldn't make a difference, as long as it was stopped? I edited a pic of someone's frame so you guys know what I'm talking about...where the yellow boxes are, there is basically a normal frame rail welded in...

 

The "Gussets" Highlighted in yellow ARE supposed to be there.
This is a VERY common spot for Rust.

 

Hmm...I didn't see them when I was looking at other pics, at least not like the ones on my car...as in, they aren't just metal plates but rails just as big as the rest of the frame...they are completely solid, it's the small area between them and the rear crossmembers that's rusted to hell

 

Rust flakes can be very misleading. Steel can expand to 64 times its size with rust. As it is a horizontal surface it is a trap for dirt and eventually rust.

The fact that that brace bent when you put a jack on it just means you jacked the wrong place. It is a brace not a jack point.

Its only steel. Cut it out and weld in some new pieces. Make up a cardboard template of the steel you need and take it to steel supplier and get him to cut them for you with his ***** steel guillitene. Get you new pieces as thick as possible. Thickness = rigidity and longevity. Weld in new pieces. If your frame is off it should be easy. If not it will be a handful but can be done. You should get out of it for under $30 if you have access to a welder. Once you are done POR-15 that steel. Etch it with OSMO or Metal Ready before you paint.

 

From what you discribe you may have major problems, You need to slide your hand up both sides of the frame where they attach to Rear crossmember to see how sound that area is also use a hammer and screw driver in that area to see if you can punch thru, If so you have major problems. I found out mine was bad by jacking up the rear end and putting jack stands in the rear corners of the frame then lower it slowly if your frame is bad it will sag in the rear and deflect in the corners. Hope this not going to happen for you. Frames are out there if you need one but shop hard i found mine on ebay for $178.00 soild with light rust. Good Luck John

 

Thanks for the advice...but I didn't jack on that brace (the gusset). I jacked on the side rail, a few inches from the rear edge...I'm not an idiot ya know The rust is at the back of the side rail, just in front and parallel to the rear tires...

 

I don't think it's that bad...if I remember correctly, the area that you're talking about is decently solid...thanks for the advice, I'll check it out when I get home.

 

ttt...any other opinions?

 

just like johns73 said take a hammer and a screwdriver and check
or get a body hammer with a pick on the end and start checking.
tap on the frame and the crossmember to look for weak spots or soft spots. also check on top of the crossmember where the trailing arm attaches. if the frame bent from just jacking it sounds very weak.

 

This is what that gusset should look like (with the exception of the sand from my blaster :o )

 

The rear kick ups are a common place for rust on C3's and also a bad place. These cars have been known to break in half when the frame rusts thru in the kick up area.

All is not lost though. The best way to repair is to remove the body and have a new piece of frame welded in. Instead of that you can get a good welder to strengthen the area by welding pieces into the areas where the rust is cut out. I had it done on my 70 for about $600 4 years ago and no problems since.

It needs to be addressed as it can be a dangerous situation if left alone.

 

Phew...wow, that is an absolute relief. I was scared as hell that I was going to have to abandon my heads/cam/intake plans and dump a couple thousand into getting the body removed and having that part entire part of my frame replaced...I should have enough spare money this summer to cough up the $600

Thanks for the all the advice guys...but once again, the pic that lostpatrolman posted is NOT what the gusset looks like on my car. On mine, it is a metal rail, just like the rest of the frame rails...

 

There's one section where there's a split running down the side rail for a few inches, and it's in this area where the part of the frame that's split off bent up...

 

[QUOTE=72Tornado]Phew...wow, that is an absolute relief. I was scared as hell that I was going to have to abandon my heads/cam/intake plans and dump a couple thousand into getting the body removed and having that part entire part of my frame replaced...I should have enough spare money this summer to cough up the $600

Thanks for the all the advice guys...but once again, the pic that lostpatrolman posted is NOT what the gusset looks like on my car. On mine, it is a metal rail, just like the rest of the frame rails...[/QUOTE]

...About that metal rail in lieu of a gusset. A description of all the 1963 to 1982 frames can be found at http://www.71corvette.com/frames.html
If you can't find a picture of your frame, someone prior to you has made a modification. Notice that for C3's, it appears that only the 1980 to 1982 frames are the frames that don't have gussets.

 

His $600 estimate (I assume) is for frame repairs AFTER the
body is off. If someone says they can repair those corners
with the body on - they are only patching it and delaying problems.

I patched mine with the body on (looked fairly decent).
Then, when I removed the body .... well, let's just say I was
know for removing LOTS of rust. If/when you lift the body,
you may (probably will) find other rust issues. This, assuming the
birdcage is still intact - allowing you to lift the body.

I ain't sugar-coating it. You have serious problems.

 

My frame looked like you described yours and when I lifted the body off I found there to be no frame left

Stp

 

I believe he's saying he had a patch job done with the body on for $600 four years ago that has so far held up fine. This doesn't need to be an ultra permanent fix, because a) once the summer ends, my car is barely going to get driven (going to college and will have to find somewhere to park it) and b) I just need something which can make it so I don't have anything to worry about in the near future, because come next summer I will save money from my job to put towards replacing that part of the frame.

Just out of curiosity, how much would it cost to go all the way, have the body lifted, and have someone replace the frame in those areas?

Oh, and as a final point, the gussets on my car definitely ARE full rails, not the small brackets usually found. These gussets are perfectly solid, so I'm not too worried

 

Well...just from taking a look at my frame and feeling around as best I can, I know it's not that far gone...that is a scary pic though

 

i thought mine was not as bad as that either but when i got my body off it was not quite as bad but very close after i removed the patch work someone else had done. their are some pics. of my frame work in my pics. as nh vette said sounds like you have some serious problems and it is not going to be cheap, fast or easy to repair even if you get someone to do the repair work. i dont know if i would spend money on other things before i repaired or got an idea of the extent of the damage. i have 1200.00 in a 74 i bought for parts (frame repair) and about 40 hrs in repairing it my self. i have heard a lot of horror storys about what people have tied up in their car and then they get very upset at the money pit and sell it at a loss (project) just because they got sick of it. you also should look very close for birdcage damage it is very common. it would be very wise to know what you have and what kind of expense you are looking at before it turns into something that makes you sick to think about. these cars are very expensive to repair and restore i will have about 16k to 18 k in mine when it is done and should be very nice. i bought very complete and just needed a little fixing up (i thought).
i am not trying to discourage you just makeing you aware.